Amniotic Fluid Index (AFI) Normal Range at 39 Weeks
May 23, 2022
Source: Cainiu Health
Dr. Lv Aiming
Introduction
At 39 weeks of gestation, the normal amniotic fluid index (AFI) ranges from 8 to 18 cm (not mm), and the normal single deepest vertical pocket (SDVP) measurement is 2–8 cm. An AFI less than 5 cm indicates oligohydramnios (low amniotic fluid volume), while an AFI greater than 25 cm suggests polyhydramnios (excess amniotic fluid). Similarly, an SDVP less than 2 cm indicates oligohydramnios, and an SDVP greater than 8 cm suggests polyhydramnios.
It is advisable to increase oral fluid intake, particularly soups and water, to help augment amniotic fluid volume. If necessary, intravenous hydration may be administered to increase amniotic fluid volume.
The amniotic fluid index (AFI) is calculated by dividing the uterus into four quadrants at right angles and measuring the vertical diameter of the largest amniotic fluid pocket in each quadrant. The sum of these four measurements yields the AFI. What is the normal AFI range at 39 weeks’ gestation?
Normal AFI Range at 39 Weeks’ Gestation
At 39 weeks, the normal AFI ranges from 8 to 18 cm, and the normal single deepest vertical pocket (SDVP) measurement is approximately 2–8 cm. An AFI < 5 cm indicates oligohydramnios (low amniotic fluid volume); an AFI < 8 cm suggests borderline low amniotic fluid. Conversely, an AFI > 24 cm indicates polyhydramnios (excess amniotic fluid); an AFI > 18 cm warrants close clinical evaluation. Increasing oral fluid intake—such as soups, soy milk, and milk—may help augment amniotic fluid volume. Intravenous hydration may be indicated when clinically necessary.
A normal AFI is 5–24 cm. An AFI > 24 cm signifies polyhydramnios, which may stem from fetal anomalies (e.g., neural tube defects, gastrointestinal obstructions) or physiological causes (e.g., maternal diabetes). Close monitoring and management under physician guidance are essential to prevent complications such as placental abruption during labor or postpartum hemorrhage. To help prevent polyhydramnios, avoid excessive salt intake and limit overhydration. Conversely, an AFI < 5 cm indicates oligohydramnios. In such cases, increasing oral hydration—including water, soy milk, and milk—may help improve amniotic fluid volume. When indicated, amniocentesis may be performed to assess fetal well-being and rule out structural anomalies.
If a fetal anomaly is confirmed, termination of pregnancy may be recommended under medical supervision to prevent adverse impacts on the baby’s postnatal development. Regular obstetric ultrasound examinations throughout pregnancy are crucial for monitoring amniotic fluid volume and fetal well-being. We hope this information is helpful!
